Telephone-transmitter.



No. 653,72l. Patented July l7, I900. .1. L. WEST.

TELEPHONE TRANSMITTER.

(Application filed mr. 8, 1900.)

(No Model.)

Wilgcsses UNITED STATES PATENT ()rrrcn.

JAMES LEWIS WEST, OF OMAHA, NEBRASKA.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 653,721, dated July 17, 1900. Application filed March 8,1900. $erial No, 7,896. (No model.)

To LZ/ZZ whom it may concern:

Be it known that I, JAMES Lnwrs Wnsr, a citizen of the United States, residing at Omaha, in the county of Douglas and State of Nebraska, have invented a new and useful Telephone-Transmitter, of which the following is a specification.

This invention relates to telephone-transmitters in general, and more particularly to the class of microphone-transmitters, one object of the invention being to provide a construction of granular-carbon transmitter in which packing of the carbon will be prevented, in which the carbon maybe accurately placed to the proper amount, and in which there will be little or no resistance to the vibration of the diaphragm.

A further object of the invention is to provide a construction in which there will be no objectionable noises produced.

Additional objects of the invention will be apparent from the following description:

In the drawings forming a portion of this specification, and in which like numerals of referenceindicate similar parts in both views, Figure 1 is a perspective view showing a complete transmitter constructed in accordance with the present invention. Fig. 2 is a central longitudinal section of the transmitter and showing the construction and arrangement of the carbon-holding cup.

Referring now to the drawings, the transmitter of the present invention comprises a preferably disk-shaped plate 5, adapted to be screwed or otherwise secured into the opening in the front of the transmitter-box, and this plate has the usual central sound-opening, to which leads the mouthpiece 6 to direct the sound-waves to the diaphragm. The diaphragm 7 is disposed against a washer 8, of paper or other suitable material, in an annular recess in the back of the plate, and in the present instance the diaphragm has a binding 9, of rubber or similar material, which rests directly against the said washer. To hold the diaphragm in its place in the recess in plate 5, spring-fingers 10 are screwed at one end upon the rear face of the plate, while their opposite ends are provided with rubber caps or tips 11, which bear against the binding 9. The fingers are held in place by screws to permit their ready adjustment into and out of operative position to hold the diaphragm in place or allow its removal.

One electrode of the transmitter consists of a carbon cylinder 12, which is rigidly connected with the central portion of the diaphragm 7 through the medium of a headed bolt 13, passed through a central perforation in the cylinder and an alining perforation in the diaphragm. This bolt is of conductive material and electrically connects the cylinder with the diaphragm. The opposing electrode is mounted upon a U-shaped plate 15, the extremities of which are bent outwardly and connected to the back of the plate 5, this plate being disposed diametrically of the plate 5, as shown, and with its Web 17 opposite to the cylindrical electrode 12, so that said electrode lies between the arms of the plate 15.

The electrode upon the plate 15 is in the form of a carbon cylinder 20 and is inclosed by a cylindrical metallic box 21, the electrode being held in place by a bolt 22, which is passed through the electrode, then through the bottom of the box, and finally through the web of the plate 15, the nut 24 of the bolt lying against the outer face of the web of the plate and forming a means for clamping a conducting-wire in electrical relation to the electrode.

The box 21 has a cap or cover 25, which is screwed onto the box, and the central portion of the cap or cover is cut away to form an opening to receive the electrode 12. The opening in the cap is somewhat greater in diameter than the electrode, and in order to secure a close fit around the electrode and at the same time to prevent electrical contact between the electrode and the cap a ring 27 of mica is clamped between the box and its cap, the interior diameter of the ring being such as to fit closely to the electrode 12, but without retarding the movement of said electrode under the influence of the vibrations of the diaphragm.

Within the box 21 and between the electrodes is disposed a mass of granular carbon 30 in such quantity that when the electrode 12 is moved by the vibrations of the diaphragm there will be always a path of varying resistance for the flow of current between the electrodes.

i Connection between the local circuit and the electrode 12 is made by means of a binding-post 35, which is mounted upon an insulating-block 36 upon the plate 15, this post being in turn connected by means of a flexible wire 37 with a metallic plate 38, which is soldered to the back face of the diaphragm and near the edge of the latter. The operation of this diaphragm will bereadily understood by those skilled in the art, and it will be seen that with the present structure all passing of current from one electrode to the other, excepting through the granular carbon, is prevented, while there is practically no resistance whatever to the vibration of the diaphragm, with the electrode thereon, excepting that ofiered by the granular carbon.

To facilitate filling of the box 21 with the proper quantity of carbon, openings 39 are formed in the side of the box beyond the electrode fixed therein, and the box is provided with a lining of mica 40, which covers these openings andpermits an inspection of the interior of the box Without permitting escape of the carbon therefrom.

It will of course be understood that in the manufacture of the present invention any suitable materials may be used for the various parts and that any suitable proportions may be observed without departing from the spirit of the invention.

What is claimed is 1. In a telephone-transmitter, the combination with a supporting-plate having a diaphragm mounted thereon, of an electrode movable with the diaphragm, a box held ad jacent to the diaphragm, an electrode in the box, granular conductive material in the box and in contact with the electrodes, openings in the sides of the box having transparent closures, a cap for the box having an opening in which the first electrode operates, and an insulatin g-rin g bridging the interspace between the first electrode and the sides of the box to prevent egress of the granular conductive material.

2. In a telephone-transmitter, the combination with a supporting-plate having a diaphragm mounted thereon, of an electrode movable with the diaphragm, a plate disposeddiametrically of the supporting-plate, a box mounted on the last-named plate, an electrode in the box in operative relation to the first electrode, openings in the side of the box, a transparent lining for the box covering the openings, a cap for the box having an opening in which the first electrode operates, an insulating-ring clamped between the box and its cap, said ring closely encircling the first electrode to prevent egress between it and the box and a filling of granular conductive material for the box.

In testimony that I claim the foregoing as my own I have hereto affixed my signature in the presence" oftwo witnesses.

JAMES LEWIS WEST.

\Vitnesses:

LYDIA S. MCAGUE, L. D. SPAULDING. 

